Free T4 test cost in Vallejo, CA
In Vallejo, CA, 3 hospitals list a cash price for free T4 (free thyroxine) thyroid blood test: from $102.48 to $230.00, with a median of $102.48. The lowest listed price is at Kaiser Foundation Hospital & Rehab Center - Vallejo and 1 other hospital. Across California, the median is $68.12 at 104 hospitals.
Cash prices at 3 facilities across 3 cities for code 84439, as an outpatient — the setting a self-pay patient normally buys. Collected Sep 23, 2026; the hospital files themselves were last updated between Apr 1, 2026 and Apr 1, 2026.
Where each hospital's price falls
Each dot is one hospital's cash price on a scale from the lowest to the highest in Vallejo, CA.
Hospitals, cheapest first
| Hospital | Cash price | List price | Insurers pay | Off list | File date |
|---|---|---|---|---|---|
| Kaiser Foundation Hospital & Rehab Center - Vallejo lowest Vallejo, CA · (707) 651-1000 ASSAY OF FREE THYROXINE | $102.48 | $183.00 | $8.00–$25.00 | 44% | — source file |
| Kaiser Foundation Hospital - Vacaville lowest Vacaville, CA · (707) 624-4000 ASSAY OF FREE THYROXINE | $102.48 | $183.00 | $8.00–$25.00 | 44% | — source file |
| NorthBay Medical Center Fairfield, CA · (707) 646-5000 T4 Free | $230.00 | $230.00 | — | — | Apr 1, 2026 source file |
| NorthBay Medical Center Fairfield, CA · (707) 646-5000 T4 Free | $230.00 | $230.00 | — | — | Apr 1, 2026 source file |
Outpatient: lowest $102.48, median $102.48, highest $230.00 — a 2.2× difference within the same market.
As an inpatient, the same code is billed by 3 facilities here, median $102.48. Inpatient and outpatient prices are not comparable and are kept on separate pages: the inpatient charge covers admission, not the same purchase.
Cash or insurance?
At 0 of 2 hospitals that publish insurer rates for this code here, the cash price is below the highest rate a health plan has negotiated, and at none is it below every plan's rate. If you have insurance but have not met your deductible, you usually pay your plan's negotiated rate, which falls somewhere in the "Insurers pay" column. Paying cash can cost less, but a cash payment usually does not count toward your deductible. Ask the hospital for both numbers before you book.
What it is
A free T4 test measures thyroxine that is not bound to proteins, the active form of the main thyroid hormone. It is usually ordered with or after a TSH test to check for an underactive or overactive thyroid and to adjust thyroid medicine.
What the price covers
The price usually covers the free T4 test only. The blood draw and the TSH test (84443) are billed separately.